Patent Application
20160247623
This application claims benefit of priority to Japanese Patent Application 2015-034667 filed Feb. 25, 2015, the entire content of which is incorporated herein by reference.
The present disclosure relates to electronic components, and more particularly to an electronic component, such as a common mode choke coil, that includes a coil conductor and a magnetic resin material.
Japanese Unexamined Patent Application Publication No. 2013-153184 discloses a common mode choke coil. The common mode choke coil disclosed in Japanese Unexamined Patent Application Publication No. 2013-153184 includes a ferrite substrate formed of a ferrite sintered compact, such as Ni—Zn ferrite. An insulating layer formed of a cured thermosetting polyimide resin material is formed on the ferrite substrate. In the insulating layer, coil conductor layers formed of conductive materials, such as Cu, Au, Al, or Ag, are formed so that the conductor layers are surrounded by the insulating layer. On the insulating layer containing the central part (magnetic core part) of the coil conductor layer, a composite ferrite resin layer formed of an epoxy resin material containing ferrite particles is formed.
In the aforementioned common mode choke coil, for example, Ni—Zn ferrite is used for ferrite particles (oxide magnetic material) for high frequency. However, Ni—Zn ferrite powder has many open pores and thus the epoxy resin material may fail to contain 62 vol % or more of ferrite particles. In this case, the composite ferrite resin layer has a low magnetic permeability μ (μ<6), which is not suitable to ensure sufficiently high impedance values (Z values) in a high-frequency area of the common mode choke coil, for example, at 100 MHz.
Accordingly, it is a primary object of the present disclosure to provide an electronic component that can ensure high impedance values.
An electronic component according to one embodiment of the present disclosure includes a laminate including insulating layers stacked in a thickness direction and having a recess recessed in a stacking direction of the insulating layers; and at least one coil conductor provided in the laminate, wherein the recess is filled with a magnetic resin material. The magnetic resin material is formed of a magnetic powder-containing resin that is a mixture of a soft magnetic metal powder and a thermosetting resin. The soft magnetic metal powder has an average particle size of 12 μm or less, and the magnetic powder-containing resin contains 65 vol % or more and 85 vol % or less of the soft magnetic metal powder.
In the electronic component according to the embodiment of the present disclosure, the soft magnetic metal powder is preferably formed of a crystalline Fe—Ni alloy or a crystalline Fe—Si alloy, and the thermosetting resin is preferably formed from an aromatic tetracarboxylic dianhydride and an aromatic diamine.
In the electronic component according to the embodiment of the present disclosure, the soft magnetic metal powder preferably has a surface with an insulating coating.
In the electronic component according to the embodiment of the present disclosure, the magnetic resin material filling the recess of the laminate is formed of a magnetic powder-containing resin that is a mixture of a soft magnetic metal powder and a thermosetting resin. The soft magnetic metal powder has an average particle size of 12 μm or less, and the powder-containing resin contains 65 vol % or more and 85 vol % or less of the soft magnetic metal powder. The electronic component according to the embodiment of the present disclosure thus achieves increased Z values (increased μ values) in a higher frequency area to provide electronic components, such as common mode choke coils, used as common mode filters for high frequency differential transmission.
When the soft magnetic metal powder is formed of a crystalline Fe—Ni alloy or a crystalline Fe—Si alloy and the thermosetting resin is formed from an aromatic tetracarboxylic dianhydride and an aromatic diamine in the electronic component according to the embodiment of the present disclosure, increased Z values (increased μ values) are achieved in a much higher frequency area and the filling ability and printing ability of the magnetic resin material can be improved due to reduced viscosity.
When the soft magnetic metal powder has a surface with an insulating coating in the electronic component according to the embodiment of the present disclosure, increased Z values (increased μ values) and increased Q values are achieved in a much higher frequency area and electronic components, such as common mode choke coils, used as common mode filters for high frequency differential transmission are provided.
According to the embodiment of the present disclosure, an electronic component that can ensure high impedance values is obtained.
Other features, elements, characteristics, and advantages of the present disclosure will become more apparent from the following detailed description of embodiments of the present disclosure with reference to the attached drawings.
Hereinafter, the stacking direction of the common mode choke coil 10 illustrated in
The common mode choke coil 10 has a rectangular parallelepiped shape as illustrated in
The laminate 12, as illustrated in
As illustrated in
The laminate 12 further includes a recess 30, as illustrated in
The recess 30, as illustrated in
The recess 30 is filled with the magnetic resin material 21 (insulating material) as illustrated in
The coil conductors 16a (first coil conductor) and 16b (second coil conductor) are provided in the laminate 12 and electromagnetically coupled to each other to form a common mode choke coil, as illustrated in
The extended conductor 17a is provided on a surface of the insulating layer 28b of the laminate 12, the surface facing in the positive z-axis direction, as illustrated in
The extended conductor 17b is provided on a surface of the insulating layer 28c of the laminate 12, the surface facing in the positive z-axis direction, as illustrated in
As illustrated in
As illustrated in
The via hole conductor v1, as illustrated in
As illustrated in
As illustrated in
On the surface of the insulating layer 28a of the laminate 12 in the positive z-axis direction, the magnetic resin material 22 is provided in the form of a layer as illustrated in
As illustrated in
In the common mode choke coil 10 having the above configuration, the coil conductors 16a and 16b are aligned with each other in top view. This allows a magnetic flux generated by the coil conductor 16a to pass through the coil conductor 16b and allows a magnetic flux generated by the coil conductor 16b to pass through the coil conductor 16a. Thus, the coil conductor 16a is magnetically coupled to the coil conductor 16b, so that the coil conductor 16a and the coil conductor 16b constitute a common mode choke coil. The outer electrodes 14a and 14b are used as input terminals, whereas the outer electrodes 14c and 14d are used as output terminals. That is, differential transmission signals are inputted from the outer electrodes 14a and 14b and outputted from the outer electrodes 14c and 14d. When differential transmission signals contain common mode noise, the coil conductors 16a and 16b generate magnetic fluxes in the same direction due to the common-mode noise current. Thus, the magnetic fluxes intensify each other to generate impedance for the common-mode noise current. As a result, the common-mode noise current is converted into heat and prevented from passing through the coil conductors 16a and 16b. When a normal-mode current flows, the coil conductors 16a and 16b generate magnetic fluxes in opposite directions. The magnetic fluxes thus cancel each other to generate no impedance for the normal-mode current. Therefore, the normal-mode current can pass through the coil conductors 16a and 16b.
Next, a description is made of an exemplary method for producing the common mode choke coil 10. A method for producing a single common mode choke coil 10 will be described below. Practically, a mother laminate in which a plurality of laminates 12, magnetic resin materials 22, adhesive layers 24, and magnetic substrates 29 are jointed together is prepared and cut into chips. The outer electrodes 14a to 14d are then formed on the chips to give common mode choke coils 10.
First, the insulating layer 28e formed of a polyimide resin or a polyimideamide resin is formed on the magnetic substrate 31. Specifically, the magnetic substrate 31 is coated with a resin layer by spin coating to form the insulating layer 28e.
On the formed insulating layer 28e, the extended conductor 17d mainly composed of a highly conductive material, such as Ag, Cu, or Au, is formed by photolithography. Specifically, a metal film is formed over the surface of the insulating layer 28e by, for example, plating, vapor deposition, or sputtering. The metal film is coated with a photosensitive resist film, followed by exposure to light and development. After that, an area of the metal film exposed from the photosensitive resist film is removed by etching, and the photosensitive resist film is then removed by an organic solvent. The extended conductor 17d is accordingly formed.
Next, the insulating layer 28d formed of a polyimide resin or a polyimideamide resin is formed on the insulating layer 28e and the extended conductor 17d by photolithography. Specifically, the insulating layer 28e is coated with a photosensitive resin film by spin coating. The photosensitive resin film is subjected to exposure to light and development to form the insulating layer 28d having a via hole to be used for the via hole conductor v2.
On the formed insulating layer 28d, the coil conductor 16b, the extended conductor 17c, and the via hole conductor v2 that are mainly composed of a highly conductive material, such as Ag, Cu, or Au, are formed by photolithography. Specifically, a metal film is formed over the surface of the insulating layer 28d by, for example, plating, vapor deposition, or sputtering. At this time, the via hole of the insulating layer 28d is filled with metal to form the via hole conductor v2. The metal film is coated with a photosensitive resist film, followed by exposure to light and development. After that, an area of the metal film exposed from the photosensitive resist film is removed by etching, and the photosensitive resist film is then removed. The coil conductor 16b, the extended conductor 17c, and the via hole conductor v2 are accordingly formed.
Thereafter, the step of forming the insulating layer 28d, and the step of forming the coil conductor 16b, the extended conductor 17c, and the via hole conductor v2 are repeated similarly. This forms the insulating layers 28a to 28c, the coil conductor 16a, the extended conductors 17a and 17b, and the via hole conductor v1. The laminate 12 is completed through the above process (first process).
Furthermore, the recess 30 is formed using a dry film resist and sandblasting (second process). More specifically, a photosensitive resin film is attached to the insulating layer 28a. After attachment, an area other than the recess 30 (photo-receiving area) is irradiated with light. An area that is not irradiated with light (non-photo-receiving area) is then removed by development. Subsequently, the area subjected to the removal by development is sandblasted. The insulating layers 28a to 28e and the magnetic substrate 31 are accordingly abraded by sandblasting to form the recess 30. Sandblasting allows the recess 30 to penetrate the insulating layers 28a to 28e. The bottom of the recess 30 reaches the magnetic substrate 31. Since the recess 30 is simultaneously formed in the insulating layers 28a to 28e and the magnetic substrate 31 by using sandblasting, the inner circumferential surface S10 of the recess 30 is smooth with no edges. After the recess 30 is formed, the photo-receiving area of the photosensitive resin film is removed.
Next, by screen printing, the magnetic resin material (insulating material) is forced into the recess 30 and the magnetic resin material 22 is formed in the form of a layer (third process). Specifically, a magnetic powder-containing resin paste is placed on the insulating layer 28a, and in this state, a squeegee is pushed and slid against the insulating layer 28a. Then, the magnetic powder-containing resin paste is thermally cured. Accordingly, the magnetic resin material 21 is forced into the recess 30 and the magnetic resin material 22 is formed.
The magnetic powder-containing resin used for forming the magnetic resin materials 21 and 22 is a material mixture of a soft magnetic metal powder and resin varnish containing an aromatic tetracarboxylic dianhydride and an aromatic diamine dissolved in an organic solvent. In this case, the soft magnetic metal powder has an average particle size of 12 μm or less (preferably 5.0 μm) and an aspect ratio of, for example, 0.65. The magnetic powder-containing resin used contains 65 vol % or more and 85 vol % or less of the soft magnetic metal powder. Furthermore, a crystalline Fe—Ni alloy or a crystalline Fe—Si alloy is preferably used as the soft magnetic metal powder in order to ensure higher magnetic permeability μ and Z values. The surface of the soft magnetic metal powder preferably has an insulating coating with an insulator containing, for example, Si and P.
Examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride (PMDA), 3,3′,4,4′-biphenyl tetracarboxylic acid (BPDA), 2,2-bis(3,4-dicarboxyphenyl)hexafluoropropane dianhydride (6FDA), 3,3′,4,4′-benzophenone tetracarboxylic dianhydride, 2,2′,3,3′-benzophenone tetracarboxylic dianhydride, 2,3,3′,4′-benzophenone tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, and naphthalene-1,2,6,7-tetracarboxylic dianhydride.
Examples of the aromatic diamine include 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-diaminomesitylene, 2,4-toluenediamine, m-phenylenediamine, 3,3′-diaminodiphenylethane, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, benzidine, 3,3′-diaminobiphenyl, 3,3′-dimethyl-4,4′-diaminobiphenyl, 3,3′-dimethoxybenzidine, and 4,4″-diamino-p-terphenyl.
Examples of organic solvents used for dissolving the aromatic tetracarboxylic dianhydride and the aromatic diamine include N-methylpyrrolidone (NMP) and γ-butyrolactone.
Examples of the crystalline Fe—Ni alloy include 78 permalloy (permalloy A), 36 permalloy (permalloy D), 45 permalloy (permalloy B), and 42 permalloy. Examples of the crystalline Fe—Si alloy include silicon steels (e.g., 6.5% silicon steel and non-oriented silicon steel), Fe—Si—Cr alloys (e.g., Fe-4Si-5Cr and Fe-5Cr-3Si), and Sendust alloys (Fe-9.5Si-5.5Al). These alloys may be used alone or in combination as soft magnetic metal powder.
The magnetic resin materials 21 and 22 are cured at curing temperatures of 250° C. or more. The cured magnetic resin materials 21 and 22 without any defects are obtained, as long as the equivalent ratio of the aromatic tetracarboxylic dianhydride and the aromatic diamine ranges from 80:100 to 100:80.
Subsequently, a thermosetting adhesive, such as an epoxy resin, is applied to the magnetic resin material 22 to form the adhesive layer 24. The magnetic substrate 29 is attached to the adhesive layer 24. Subsequently, the magnetic resin material 22 and the magnetic substrate 29 are bonded to each other by performing heating.
Next, an assembly of the laminate 12, the magnetic resin material 22, the adhesive layer 24, and the magnetic substrate 29 is cut into chips by dicing. The chips are subjected to barrel finishing for chamfering.
Next, conductor films mainly composed of Ag are formed on the laminate 12, the magnetic resin material 22, the adhesive layer 24, and the magnetic substrate 29 by using a shield plate, such as a metal mask.
Finally, the conductor films are subjected to Ni/Sn plating to form the outer electrodes 14a to 14d. The common mode choke coil 10 is completed according to the above process.
In the common mode choke coil 10, the magnetic resin material 21 filling the recess 30 of the laminate 12 is formed of a magnetic powder-containing resin that is a mixture of a soft magnetic metal powder and a thermosetting resin. The soft magnetic metal powder has an average particle size of 12 μm or less, and the magnetic resin material is a magnetic powder-containing resin containing 65 vol % or more and 85 vol % or less of the soft magnetic metal powder. The common mode choke coil thus achieves increased Z values (increased μ values) in a high-frequency area, and can be used as, for example, a common mode filter adapted for high frequency differential transmission.
In particular, the coil conductors 16a and 16b are magnetically coupled to each other in the common mode choke coil 10, and the magnetic coupling is enhanced by using the magnetic resin material 21 in a magnetic core part (central part of the coil conductors 16a and 16b) to increase common mode impedance values (Z values), while the reduced direct current resistance (Rdc) is achieved due to the reduced number of windings of the coil conductors.
When the soft magnetic metal powder is formed of a crystalline Fe—Ni alloy or a crystalline Fe—Si alloy and the thermosetting resin is formed from an aromatic tetracarboxylic dianhydride and an aromatic diamine in the common mode choke coil 10, increased Z values (increased μ values) are achieved in a much higher frequency area and the filling ability and printing ability of the magnetic resin materials 21 and 22 can be improved due to reduced viscosity.
When the soft magnetic metal powder has a surface with an insulating coating in the common mode choke coil 10, increased Z values (increased μ values) and increased Q values are achieved in a much higher frequency area and the common mode choke coil 10 is used as, for example, a common mode filter adapted for high frequency differential transmission.
In Experimental Example 1, the common mode choke coil 10 illustrated in
In this case, the metal kind, crystallinity, average particle size, and fill volume of the soft magnetic metal powder for forming the magnetic resin materials 21 and 22 were listed in the conditions shown in Table 1.
A polyimide resin was used as a material of the insulating layers 28a to 28e.
Silver (Ag) was used as a material of the coil conductors 16a and 16b, the extended conductors 17a to 17d, and the via hole conductors v1 and v2.
The common mode choke coil 10 was formed to have outer dimensions of 0.45 mm×0.30 mm×0.30 mm.
The real part μ′ and imaginary part μ″ of the magnetic permeability μ and the magnetic permeability μ of a ring-shaped material (toroidal core) of the magnetic resin materials 21 and 22 are determined as the material characteristics of the common mode choke coil 10. The impedance value of the common mode choke coil 10 was determined as the product characteristics of the common mode choke coil 10.
The material characteristics and product characteristics were measured using “Agilent E4991A RF impedance/material analyzer (Agilent Technologies, Inc.)” as a characteristic measuring device for determining the material characteristics and product characteristics. In this case, the ring-shaped material (toroidal core) of the magnetic resin materials 21 and 22 was introduced into a cavity resonator. The Z value, the L value, and the R value were obtained from the change in impedance of the toroidal core before and after the introduction, and the μ′ value and the μ″ value were further calculated. The impedance value (Z value) of the common mode choke coil 10 at 100 MHz was determined as the product characteristics of the common mode choke coil 10.
The results of the material characteristics and the product characteristics were summarized in Table 1.
The results shown in Table 1 indicate that common mode filter characteristics, that is, characteristics with a Z value of 58.5Ω or more at 100 MHz are obtained when the fill volume of 42 permalloy (powder having an average particle size D50 of 5.0 μm) as soft magnetic metal powder ranges from 65 vol % or more and 85 vol % or less. The specification of the common mode choke coil 10 is as follows: the nominal value, maximum value, and minimum value of impedance are 90.0 Ω, 121.5Ω, and 58.5Ω respectively with an acceptable range of 90 Ω±35%, as shown in Table 1.
The common mode choke coil 10 within the scope of the present disclosure can accordingly ensure a high impedance value.
The common mode choke coil 10 illustrated in
In this case, the metal kind, crystallinity, insulating coat (insulating coating), average particle size, and fill volume of the soft magnetic metal powder for forming the magnetic resin materials 21 and 22 were listed in the conditions shown in Table 2.
In the insulating coating of the soft magnetic metal powder, Fe42Ni (crystal), Fe—Si—Cr (crystal), and Fe—Si (crystal) were treated with phosphate coating using a P-containing phosphate coating agent and Fe—Si—Cr (amorphous) was treated with silane coupling using a Si-containing silane coupling agent. The phosphate coating treatment is a typical conversion coating method and is used to form a thin film (micron-order film) of metal salts, such as zinc phosphate, on the surface of metals, such as steel and zinc. The silane coupling treatment is a typical method for forming strong chemical bonding by adhesion of a silane coupling agent on an inorganic surface through hydrogen bonding and causing a dehydration/condensation reaction and is used to form a thin film (tens-micron-order film) of oxides, such as silicon oxide, on the surface of metals, such as steel and zinc. In particular, a soft magnetic metal powder having a small particle size (average particle size) may be subject to oxidation combustion, and thus requires insulating coating to prevent oxidation combustion.
A polyimide resin was used as a material of the insulating layers 28a to 28e, as in Experimental Example 1.
Silver (Ag) was used as a material of the coil conductors 16a and 16b, the extended conductors 17a to 17d, and the via hole conductors v1 and v2.
The common mode choke coil 10 was formed to have outer dimensions of 0.45 mm×0.30 mm×0.30 mm.
The material characteristics and product characteristics of the common mode choke coil 10 were determined as in Experimental Example 1, and the results of the material characteristics and the product characteristics were summarized in Table 2.
The results shown in Table 2 indicate that common mode filter characteristics, that is, characteristics with a Z value of 58.5Ω or more at 100 MHz are obtained in the common mode choke coil 10 when the soft magnetic metal powder has an average particle size of 12 μm or less at a fill volume of the soft magnetic metal powder of 75 vol % which is within the scope of the present disclosure.
The results shown in Table 2 also indicate that the common mode choke coil 10 achieves increased Q values by insulating coating of the surface of the soft magnetic metal powder. The use of amorphous powder as soft magnetic metal powder reduces the common mode filter characteristics within the scope of objectives of the present disclosure, but may cause an increase in Q value.
The results shown in Table 2 also indicates soft magnetic metal powder that is crystalline and finer is preferably used to ensure high Z values and high Q values.
In the common mode choke coil 10, the recess 30 has a parabolic shape protruding in the negative z-axis direction in side view. The magnetic resin material 21 has a shape corresponding to that of the recess 30. In the present disclosure, the recess 30 and the magnetic resin material 21 may be formed to have other shapes, such as cylindrical shape or prism shape.
In the common mode choke coil 10, the recess 30 is formed using a dry film resist and sandblasting, but the recess 30 may be formed using laser machining.
Although the common mode choke coil 10 has two coil conductors 16a and 16b and the magnetic resin material 21, the present disclosure may be applied to other electronic components, such as inductors having one coil conductor and a magnetic resin material and filters having three or more coil conductors and a magnetic resin material. In addition, the present disclosure may be applied to electronic components having elements, such as a capacitor element, a resistance element, or an active element, in addition to a coil conductor and a magnetic resin material.
The electronic component according to the present disclosure is preferably used as an electronic component, such as a common mode choke coil, including a coil conductor and a magnetic resin material.
While preferred embodiments of the disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The scope of the disclosure, therefore, is to be determined solely by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2015-034667 | Feb 2015 | JP | national |
